AN INVESTIGATION OF THE ASSOCIATIONS BETWEEN SEVERAL CANDIDATE GENES AND REPRODUCTIVE TRAITS IN SWINE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University By Bradley J. Isler, M.S. **** The Ohio State University 2003 Dissertation Committee: Approved by Dr. Keith M. Irvin, Adviser Dr. Michael E. Davis Dr. Harold C. Hines _____________________________ Dr. Steven J. Moeller Adviser Dr. Steven M. Neal Animal Sciences Graduate Program ABSTRACT Most commonly, improvement of livestock species is accomplished using traditional methods of genetic selection. New discoveries in the field of molecular genetics now allow the isolation and study of specific regions of the genome that influence important traits. Special attention has been focused on those genes that are thought to control the physiological pathways that influence the reproductive ability of our common livestock species. Reproduction is used as both a means to propagate animals within a livestock herd and as a way to facilitate genetic improvement of the herd. Unfortunately, the genetic improvement of reproductive traits using classical methods of genetic selection is severely limited, due to the low heritability and sex-limited nature of these traits. Molecular genetics can be used to determine which animals contain reproduction-specific marker regions. These animals can then be selected for inclusion in a marker assisted selection program. The purpose of this current study was to investigate the effect of several candidate genes on reproductive performance in swine. Candidate genes were selected for investigation based on previous studies that have shown associations between the gene of interest and reproduction in swine (estrogen receptor alpha) or reproduction in other mammalian species (estrogen receptor beta, paternally expressed gene 1, paternally expressed gene 3). A population of Yorkshire, Large White, and reciprocally crossbred ii female swine were utilized in this study to investigate the associations between each of these candidate genes and a variety of reproductive tract and litter traits. Associations between genotype and reproductive traits were found for all candidate genes studied. The results of this study allow for a greater understanding of the effects of these genes and will allow researchers to determinate how these genes could be most efficiently utilized to improve reproductive performance in swine. iii Dedicated to God and my parents. iv ACKNOWLEDGMENTS I first need to thank my adviser, Dr. Keith Irvin, for all his help and advice over the past five years. I can’t imagine having a better adviser than Dr. Irvin. His calm and composed personality is the best antidote for my nervous and oftentimes frantic personality. Dr. Irvin has always been extremely supportive of all my ideas and done whatever was necessary to help me bring those ideas to fruition. I also cannot thank him enough for allowing me the opportunity to develop as a lecturer and instructor. The chance to teach an entire undergraduate class is an experience that has helped me in my career perhaps more than any experiment in any lab. Things would have been much more difficult if I had not been able to try to learn from the best teacher around. Thanks again, Dr. Irvin. Many thanks to all the members of my dissertation committee: Dr. Michael Davis, Dr. Chuck Hines, Dr. Steve Moeller, and Dr. Steve Neal. Drs. Davis and Hines gave me a place to perform experiments and pile my books in the animal genetics laboratory. Your technical advice has been very useful to me over the years. Dr. Moeller has always been the committee member to bring a different perspective to all of my research, and I thank him for that. In fact, he deserves a lot of thanks for just putting up with me on trips anywhere, with my constant comments about his driving skills and tendency to only eat at v McDonalds! Dr. Neal also deserves a great deal of thanks for continuing to drive all the way from Wooster to Xenia through the collection of 377 reproductive tracts at a ridiculous hour of the morning (or would that early actually be considered the previous night?). I also need to thank all of the genetics laboratory staff, especially Judy Riggenbach. Judy has been a huge help to me in my time in the genetics laboratory. How many times did I work myself into a corner only to have Judy bail me out? Who else would put up with my hogging of the thermal cyclers and habitually bad estimates of when my PCRs would be finished? For this and many other reasons, Judy deserves an award for the individual who displayed the greatest amount of patience in the genetics lab. Good luck to you in the future Judy! Thanks to Dave Owens and Kelly Black at OARDC Western Branch for help in collection of all those blood samples and help with reproductive data collection. I probably need to thank them as much or more for putting up with my complaint of “More blood samples?” over all these years as I do for helping with the blood collection. Is it possible that you collected over 1400 blood samples? I also couldn’t forget my partners in crime, Tim Leeds and Becky Emnett. Who else can I thank for slowing me down in graduate school so much? If Tim wouldn’t have forced me into all those ski trips and caused (possible) brain damage by pelting me in the side of the head with Vail snowballs (actually iceballs), I probably would have been done a year ago. As for Becky, how much extra time in grad school do you think was caused by vi your insistence that we drink Canadian cocktails and hang around with the homeless at Minneapolis bus stops at 2AM? Thanks a lot for all the good times, you two. Thank you to my best friend over the past 8 years, Beth, for all her love and support during my time in grad school, and especially the past few months. Poor Beth has had to put up with my lovely moods over the past year as I tried to finish everything up. Beth, I owe you a great deal for putting up with me and reassuring me when I was not sure if it was worth it or not. I’m not quite sure what the next few years will bring, but just remember that the Frog, Brutus, and I will always love you. I’ve got to thank the two people who have been there for me through the past 29 years, and the past 10 years of school in particular, my parents. If it wouldn’t have been for all the things you taught me as I was growing up, there is no way I could have made it through all these years of school. Thank you for listening to all my gripes for all these years and putting me on the right track. I love you guys a lot. Finally, thanks again to the Rocky Mountains for calming memories on bad days. vii VITA March 29, 1974 …………….……Born - Columbus, Ohio May 1996 ………………..………B.S., Biochemistry, Ohio Northern University, Ada, OH August 1996 - June 1997 ………..Graduate Research Associate, Interdepartmental Molecular, Cellular, and Developmental Biology Program, Iowa State University, Ames, IA July 1997 – December 1998……...Graduate Research Associate, Department of Animal Sciences, The Ohio State University, Columbus, OH December 1998 ………………….M.S., Animal Sciences, The Ohio State University, Columbus, OH January 1999 – Present…..……....Graduate Research Associate, Department of Animal Sciences, The Ohio State University, Columbus, OH PUBLICATIONS Isler, B.J., K.M. Irvin, S.M. Neal, S.J. Moeller, and M.E. Davis. 2002. Examination of the relationship between the paternally expressed gene 3 and reproductive tract components in swine. Poster presented at the 2002 Annual Conference of the National Swine Improvement Federation. Isler, B.J., K.M. Irvin, S.M. Neal, S.J. Moeller, and M.E. Davis. 2002. Investigation of the relationship between the estrogen receptor beta gene and reproductive components in swine. Poster presented at the 2002 Annual Conference of the National Swine Improvement Federation. viii Isler, B.J., K.M. Irvin, S.M. Neal, S.J. Moeller, and M.E. Davis. 2002. Examination of the relationship between the estrogen receptor gene and reproductive traits in swine. Journal of Animal Science. 80:2334-2339. Isler, B.J., K.M. Irvin, S.M. Neal, S.J. Moeller, and M.E. Davis. 2002. Examination of the relationship between the paternally expressed gene 3 and reproductive tract components in swine. Proceedings of the 7th World Congress of Genetics Applied to Livestock Production. CD-Rom Communication. N° 08-28. Isler, B.J., K.M. Irvin, S.M. Neal, S.J. Moeller, and M.E. Davis. 2002. Investigation of the relationship between the estrogen receptor beta gene and reproductive components in swine. Journal of Animal Science. 80(Suppl. 1): 378 (Abstract). Isler, B.J., K. M. Irvin, M.F. Rothschild, and G.J. Evans. 2001. Examination of the relationship between the prolactin receptor gene and reproductive components in swine. Research and Reviews: Swine 2001, OARDC special circular 185. 83-86. Isler, B.J., K. M. Irvin, M.F. Rothschild, and G.J. Evans. 2000. Association between the prolactin receptor gene and reproductive components in swine. Poster presented at the 2000 Annual Conference of the National Swine Improvement Federation. Isler, B.J., K. M. Irvin, M.F. Rothschild, and G.J. Evans. 2000. Association between the prolactin receptor gene and reproductive components in swine. Proceedings of the 27th Conference of the International Society of Animal Genetics. CD-Rom Communication. N° C032. (Abstract). Isler, B.J., K.M. Irvin, S.M.